Multi-level tubular reactor with internal tray

[0001] The invention relates to reactors for processing liquid-containing reaction media. In another aspect, the invention relates to polycondensation reactors used to make melt phase polyesters.

2. Description of the Related Art [0002] Melt phase polymerization can be used to make many polyesters, such as, for example, polyethylene terephthalate (PET). PET is widely used in beverage, food and other containers as well as in synthetic fibers and resins. Advances in process technology coupled with increased demand have led to an increasingly competitive PET production and sales market. Thus, a low cost, high performance PET process is desirable.

[0003] Generally, melt phase polyester installations, including those used for PET, use an esterification stage and a polycondensation stage. In the esterification step, polymer raw materials (i.e. reactants) are converted into polyester monomers and / or oligomers. In the polycondensation step, the polyester monomers leaving the esterification step are converted to a polymer product having the desired final average chain length.

[0004] In many conventional melt-phase polyester installations, esterification and polycondensation are carried out in one or more mechanically mixed reactors, such as, for example, continuous stirred tank reactors (CSTR). However, CSTR and other mechanically stirred reactors have a number of disadvantages that can lead to increased investment, operating, and / or maintenance costs for the entire polyester production facility.

For example, mechanical agitators and various control equipment typically associated with CSTR is complex, expensive, and may require complex maintenance.

[0005] Thus, there is a need for a method for producing high performance polyester that minimizes investment, operation and maintenance costs while maintaining or increasing product quality.

[0006] US6545176 discloses a method for producing methyl methacrylate or methacrylic acid and a device for increasing performance in a method for producing methyl methacrylate or methacrylic acid. A cracking step is used which takes place in the pipe, which may include a partition separating the pipe to obtain a passage having a 180 ° bend to minimize the space necessary for housing the cracking reactor.

[0007] US 2006/008661 discloses a tubular reactor comprising a horizontally elongated tubular element and a shelf disposed in a tubular element in which the shelf extends partially along the length of the tubular element and divides the interior into an upper and lower chamber. The reactor is used in a method of depositing silicon carbide on a substrate.

SUMMARY OF THE INVENTION [0008] In one embodiment of the present invention, there is provided a method of producing polyethylene terephthalate (PET) comprising subjecting a reaction medium to a chemical reaction in a reactor comprising a horizontally elongated reactor segment through which the reaction medium flows as the reaction medium passes through reactor. The reactor segment comprises a horizontally elongated tubular element and a shelf disposed substantially in the tubular element and extending along at least half the length of the tubular element. At least a portion of the reaction medium flows in one direction to the shelf and in the opposite direction to the bottom of the tubular element.

[0009] In a further embodiment of the present invention, a reactor is provided comprising a horizontally elongated reactor segment. The reactor segment includes an elongated tubular element and a shelf disposed substantially in the tubular element. The shelf extends along at least half the length of the tubular element and divides the inside of the tubular element into an upper and lower chamber. The reactor segment includes an internal flow channel near one end of the reactor segment to allow fluid to pass between the upper and lower chambers, and includes a vertically elongated chamber.

BRIEF DESCRIPTION OF THE DRAWINGS [0010] Certain embodiments of the present invention are described in detail below with reference to the attached figures, in which:

FIG. 1 schematically shows a multi-stage tubular reactor configured in accordance with one embodiment of the present invention and suitable for use as a polycondensation reactor in a melt phase polyester plant;

FIG. 1a is an enlarged side view showing an alternative configuration for introducing the feed stream into the reactor of FIG. 1;

FIG. 1b is a top view of the alternative feed introduction system illustrated in FIG. 1a;

FIG. 1c is a cross-sectional front view of the alternative feed introduction system along line 1c-1c in FIG. 1a;

FIG. 2 schematically illustrates a multilevel tubular reactor configured in accordance with another embodiment of the present invention and suitable for use as a polycondensation reactor in a melt phase polyester plant; and

FIG. 3 schematically illustrates a multilevel tubular reactor suitable for use as a polycondensation reactor in a melt phase polyester plant.

DETAILED DESCRIPTION [0011] FIG. 1 and 2 illustrate exemplary multi-level tubular reactors configured in accordance with two embodiments of the present invention. The configuration and operation of the reactors illustrated in FIG. 1 and 2 are described in detail below. Although certain parts of the description below apply primarily to reactors used in the melt phase polyester process, reactors configured in accordance with embodiments of the present invention may find application in a wide range of chemical processes. For example, reactors configured in accordance with certain embodiments of the present invention can be advantageously used in any method in which chemical reactions occur in the liquid phase of the reaction medium and a vapor by-product is formed as a result of the chemical reaction. In addition, reactors configured in accordance with certain embodiments of the present invention can be advantageously used in chemical processes in which at least part of the reaction medium forms foam during processing.

[0012] With reference to FIG. 1, one embodiment of the multilevel tubular reactor 10 is illustrated as generally comprising a vertically elongated chamber 12 and a group of horizontally elongated vertically spaced reactor segments 14 connected and projecting outwardly from the chamber 12.

[0013] The chamber 12 generally comprises a vertical tubular jacket 16, a pair of closing caps 17a, b connected to opposite ends of the jacket 16 and a plurality of deflectors 18a, b, c of flow arranged in the inner volume of the chamber 12. The first steam gap 20a is located between the deflectors 18a and 18b, while the second steam gap 20b is between the flow deflectors 18b and 18c. The chamber 12 comprises a steam outlet 22 in the upper closing cap 17a and a liquid product outlet 24 in the lower closing cap 17b. One side of the chamber 12 has a plurality of vertically spaced openings that provide fluid flow between the internal volume of the chamber 12 and a group of reactor segments 14 connected to the side of the chamber 12.

[0014] In the embodiment illustrated in FIG. 1, the jacket 16 of the chamber 12 is a substantially vertical, substantially cylindrical tube. In an alternative embodiment, the cladding 16 may be a vertically elongated tubular element having many cross-sectional configurations (e.g., rectangular, square, or oval).

In addition, the mantle 16 does not have to have a perfectly vertical orientation. For example, the central axis of jacket extension 16 may stand out by about 30, about 15, or 5 degrees from the vertical.

[0015] In the embodiment illustrated in FIG. 1, the chamber 12 has a maximum internal height (H) greater than its maximum internal width (W). In one embodiment, the chamber 12 has a height to width ratio (H: W) in the range of from about 2: 1 to about 20: 1, about 4: 1 to about 15: 1, or 5: 1 to 10: 1. In one embodiment, H is in the range of from about 2.44 to 30.48 m (about 8 to about 100 feet), about 3.05 to about 22.36 m (about 10 to about 75 feet), or , 1 to 15.2 m (20 to 50 feet) and W ranges from about 3.05 to about 6.1 m (about 1 to about 20 feet), about 0.61 to about 3.05 m ( about 2 to about 10 feet) or 0.91 to 1.52 m (3 to 5 feet).

[0016] In the embodiment illustrated in FIG. 1, the reactor segment group 14 is directly connected and extends generally outwardly from the common side of the chamber 12. The reactor segment group 14 includes the reactor 26 shelfless segment, the reactor highest plate segment 28a, the reactor intermediate plate segment 28b and the reactor lowest plate segment 28c. Each segment 26 and 28a, b, c of the reactor comprises a proximal end connected to fluid flow with chamber 12 and a distal end remote from chamber 12.

[0017] The reactor half-segment 26 includes a feed inlet 30 near its distal end and an outlet 32 ​​near its proximal end. The bedless reactor segment 26 generally includes a horizontally elongated tubular member 34 and closing cap 36. The tubular member 34 is connected to the chamber 12 near the proximal end of the non-bedded reactor segment 26, while the closing cap 36 is connected to tubular member 34 near the distal end of the half-bar segment 26 reactor. The overflow 38 may, optionally, be connected and extend upward from the bottom of the tubular member 34 near the outlet 32 ​​(as shown in FIG. 1) and / or a plurality of spaced overflows (not shown) may be located along the length of the tubular member 34 .

[0018] Each plate segment 28a, b, c of the reactor comprises a respective inlet 40a, b, c reaction medium and a corresponding outlet 42a, b, c reaction medium. Inlets 40a, b, c and outlets 42a, b, c are located near the proximal end of segments 28a, b, c of the reactor and are connected to fluid flow with the internal volume of chamber 12. Each plate segment 28a, b, c of the reactor generally includes horizontally elongated tubular element 44a, b, c, closing cap 46a, b, c and shelf 48a, b, c. The tubular elements 44a, b, c are directly connected to the chamber 12 near the proximal end of the reactor segments 28a, b, c. The end caps 46a, b, c are connected to tubular elements 44a, b, c near the distal end of segments 28a, b, c of the reactor.

[0019] The shelves 48a, b, c are arranged in respective tubular elements 44a, b, c and protrude over a considerable length of tubular elements 44a, b, c. Each shelf 48a, b, c includes a proximal end connected to a respective diverter 18a, b, c of flow and a distal end positioned near the distal end of segments 28a, b, c of the reactor. Each shelf 48a, b, c may have a length of at least about 0.5 L, about 0.75 L, or 0.9 L, where L is the maximum length of segment 28a, b, c of the reactor and / or tubular element 44a, b , c, in which the appropriate shelf 48a, b, c is placed.

[0020] Each half shelf 48a, b, c divides the internal volume of the respective segment 28a, b, c of the reactor into the upper chamber 50a, b, c and the lower chamber 52a, b, c. In the embodiment illustrated in FIG. 1, each shelf 48a, b, c includes a substantially horizontal, substantially flat, upwardly directed flow surface through which liquids may flow. To obtain a sufficiently large upper and lower chamber 50a, b, ci 52a, b, c, the upward flow surface of each shelf 48a, b, c may be spaced from the upper and / or lower tubular elements 44a, b, which is the vertical distance in range from about 0.1D to about 0.9D, about 0.2D to about 0.8D, or 0.4D to 0.6D, where D is the maximum vertical dimension of the tubular element 44a, b, c, which is suitable shelf 48, a, b, c.

[0021] The distal end of each shelf 48a, b, c is spaced from end caps 46a, b, c such that the flow channel 54a, b, c is in a gap between the distal end of each shelf 48a, b, c and end caps 46a, b, c. The distal end of each shelf 48a, b, c may optionally be provided with an upward projection 56a, b, c. Each plate segment 28a, b, c of the reactor may optionally be equipped with an overflow 58a, b, c connected and projecting upward from the bottom of the tubular elements 44a, b, c near outlets 42a, b, c.

[0022] In the embodiment illustrated in FIG. 1, the tubular elements 34 and 44a, c, b of each reactor segment 26 and 28a, b, c are substantially horizontal pipes, and the shelves 48a, b, c are substantially flat, substantially horizontal, substantially rectangular plates rigidly and tightly connected to the inner walls pipe. In an alternative embodiment, the tubular elements 34 and 44a, c, b of each segment 26 and 28a, b, c of the reactor may have different cross-sectional shapes (e.g., rectangular, square or oval). Furthermore, tubular elements 34 and 44a, c, b and shelves 48a, b, c do not need to have an exactly horizontal orientation. For example, the central axis of extension of tubular elements 34 and 44a, c, b may stand out by about 30, about 15, or 5 degrees from horizontal. In addition, shelves 48a, b, c can be supported on tubular elements 44a, b, c using a number of support mechanisms such as, for example, welding from both side walls of tubular elements 44a, b, c, supporting legs protruding from the bottom of tubular elements 44a, b, c, or suspension from the top of pipe elements 44a, b, c.

[0023] In the embodiment illustrated in FIG. 1, each segment 26 and 28a, b, c of the reactor and / or each tubular element 34 and 44a, b, c has a maximum internal length (L) that is greater than its maximum internal diameter (D). In one embodiment, each segment 26 and 28a, b, c of the reactor and / or each tubular element 34 and 44a, b, c has a length to diameter ratio (L: D) in the range of about 2: 1 to about 50: 1 , about 5: 1 to about 20: 1, or 8: 1 to 15: 1. In one embodiment, L is in the range of from about 3.05 to about 60.96 m (10 to about 200 feet), about 6.1 to about 30.48 m (about 20 to about 100 feet), or , 14 to 15.24 m (30 to 50 feet) and D is in the range of about 3.05 to about 6.1 m (about 1 to about 20 feet), about 0.61 to about 3.05 m ( about 2 to about 10 feet) or 0.91 to 1.52 m (3 to 5 feet). In one embodiment, the ratio of the diameter (L) of one or more segments 26 and 28a, b, c of the reactor to the maximum internal chamber width (W) ranges from about 0.1: 1 to about 2: 1, about 0 , 25: 1 to about 1: 1, or 0.4: 1 to 0.9: 1. In the embodiment illustrated on F1G. 1, each tray segment 28a, b, c of the reactor has a substantially identical configuration. In an alternative embodiment, the reactor segments 28a, b, c may have different lengths, different diameters and / or different orientations.

[0024] In the embodiment illustrated in FIG. 1, reactor 10 includes one non-plate reactor segment 26 and three plate segments 28a, b, c of the reactor. However, it should be noted that the number and configuration of reactor segments can be optimized to suit the application for which the reactor is used

10. For example, reactor 10 may use only plate reactor segments (i.e., no non-plate reactor segments). In this configuration, the uppermost plate reactor segment will have a feed inlet near the chamber. In another example, the reactor may use one non-plate reactor segment and two plate reactor segments. In another example, the reactor may use one non-plate reactor segment and four plate reactor segments. While FIG. 1 illustrates the feed inlet 30 being positioned in the closing cap 36, in an alternative embodiment, the feed inlet may be located at the side of the tubular member 34 near, but at a distance from, the distal end of the non-plate reactor segment 26.

[0025] FIG. 1a-c illustrate an alternative feed charge introduction system 90 that allows the reactor feed charge to be fed through the side of reactor segment 26. As perhaps best illustrated in the top view of FIG. 1b and an end view of FIG. 1c, the lateral feed introduction system 90 includes an inlet 92 located on the side of the reactor segment 26, an internal feed distributor 94 extending into the reactor segment 26, and an outlet opening 96 located in the feed distributor 94. In the embodiment illustrated in FIG. 1 ac, the feed distributor 94 is a generally cylindrical conduit that is attached to the side wall of segment 26 of the reactor at inlet 92. The distal end of the feed charge distributor 94 includes an outlet 96 at a location distant from the side walls and end of the reactor segment 26. As shown in FIG. 1 b and 1 c, the outlet opening 96 may be formed by cutting the distal end of the feed distributor 94 obliquely at an angle such that the outlet opening 96 is directed at least partially towards the closed end of the reactor segment 26. The arrangement and orientation of the outlet 96 can increase fluid circulation and help reduce or eliminate stagnation zones near the end of reactor segment 26.

[0026] Again, according to FIG. 1, during operation, a feed charge, which may be mainly in liquid form, is introduced into the reactor 10 through the feed inlet 30 of the non-shelf segment 26 of the reactor. In the non-shelf reactor segment 26, the feed feed creates a reaction medium 60 that flows generally horizontally to the bottom of the tubular member 34 from the distal end of the non-shelf reactor segment 26 to the proximal end of the non-shelf reactor segment 26. When the reaction medium 60 flows through the non-plate reactor segment 26, a chemical reaction takes place in the reaction medium 60. Steam 62 may be formed in the non-tray reactor segment 26. Steam 62 may include the by-product of the chemical reaction conducted in reactor segment 26 and / or the volatile feed component of reactor segment 26. At least a portion of the vapor 62 is separated and generally flows over the reaction medium 60 when the reaction medium 60 flows through the non-plate reactor segment 26.

[0027] As illustrated in FIG. 1, in one embodiment of the present invention, the chemical reaction carried out in the reactor 10 causes the reaction medium 60 to foam, thereby producing the foam portion 64 and the mainly fluid portion 66 of the reaction medium 60. The chemical reaction can occur in the liquid of both the foam portion 64 as well as the part being mainly liquid 66. In fact, the presence of foam can improve certain chemical reactions, especially those reactions that are facilitated by increased liquid surface area and reduced pressure. Thus, in one embodiment of the present invention, the internal volume and open flow area of ​​the reactor segments are sufficiently large that maximum foam formation is allowed. In applications where intense foaming occurs in a substantial portion of the reactor, it may be desirable to use two or more initial non-shelf reactor segments and fewer plate reactor segments to provide sufficient space in the reactor segments for maximum foam formation. Alternatively, larger plate reactor segments may be used to provide sufficient space and open flow field to promote foam formation. As illustrated in FIG. 1 and 2, the amount of foam produced in the reaction may decrease as the reaction proceeds in the reactor. Thus, the reaction medium 60 in the initial reactor segment may comprise more than 50, 75, or 90 volume percent of gas, while the reaction medium 60 in the final reactor segment may contain less than 20, 10, or 5 volume percent of gas.

[0028] Again, according to FIG. 1, after having passed through the non-shelf section 26 of the reactor, the reaction medium 60 exits the non-shelf section 26 of the reactor through the outlet 32. If overflow 38 is used, the reaction medium 60 flows over, around the edge, through the openings and / or under the overflow 38 when it leaves the non-shelf segment 26 of the reactor and enters the internal volume of the chamber 12. When the reaction medium 60 leaves the non-shelf segment 26 of the reactor and flows down to chamber 12, steam 62 flows up into the chamber 12. In chamber 12, steam 62 from the non-shelf segment 26 of the reactor can be combined with the steam produced in the shelf segments of reactor 28a, b c. The resulting combined steam can leave the chamber 12 through the steam outlet 22. After leaving the non-plate reactor segment 26, the reaction medium 60 flows downwardly in the chamber 12 and is directed through the flow diverter 18a to the inlet 40a of the uppermost plate segment 28a of the reactor.

[0029] In the highest shelf segment 28a of the reactor, the reaction medium 60 flows generally horizontally through the upwardly facing surface of the shelf 48a and towards the distal end of the reactor segment 28a. As discussed above, the reaction medium 60 is chemically reacted in the reactor segment 28a, and the chemical reaction can cause the formation of a by-product in the form of steam and / or foam when the reaction medium 60 flows through the shelf 48a. When the steam is generated by the reaction medium 60 flowing on the shelf 48a, the steam may flow in the upper chamber 50a in countercurrent to the flow direction of the reaction medium 60 in the upper chamber 50a. The steam by-product can leave the upper chamber 50a through the inlet 40a as the reaction medium 60 enters the upper chamber 50a through the inlet 40a.

[0030] When the reaction medium 60 reaches the end of the shelf 48a, it falls down through the flow channel 54a and to the bottom of the tubular element 44a. When the end of the shelf 48a is equipped with an overflow 56a, the reaction medium 60 flows over, around the edge, through the openings and / or under the overflow 56a before entering the flow channel 54a. Reaction medium 60 then flows to the bottom of tubular member 44a from the distal end of reactor segment 28a to the proximal end of reactor segment 28a. When the reaction medium 60 reaches the proximal end of the reactor segment 28a, it leaves the reactor segment 28a through the outlet 42a and enters the chamber 12. When steam by-product is formed in the lower chamber 52a, the steam generally flows over the reaction medium 60 and leaves the lower chamber 52a together with reaction medium 60 through outlet 42a. When the overflow 58a occurs at the outlet 42a, at least a portion of the reaction medium 60 flows over, around the edge, through the openings and / or under the overflow 58a.

[0031] Overflows 38, 56a, b, c, and 58a, b, c can be used in reactor 10 to help maintain the desired depth of reaction medium 60 in segments 26 and 28a, b, c of the reactor. In one embodiment of the present invention, the maximum depth of reaction medium 60 in each segment 26 and 28a, b, c of the reactor is less than about 0.8D, less than about 0.4D, or less than 0.25D, where D is the maximum vertical dimension of the corresponding segment 26 and 28 a, b, c reactor.

[0032] When the reaction medium 60 leaves the top plate segment 28a of the reactor and flows downwards in the chamber 12, the steam generated in the plate segment 28a of the reactor flows up into the chamber 12. The steam leaving the bottom chamber 52a of the segment 28a of the reactor can pass through the gap 20a into steam located in the flow diverter 18b or between the flow deflectors 18a and 18b. As mentioned above, the steam generated in the reactor segment 28a can be combined in the chamber 12 with the steam generated in the non-shelf segment 26 of the reactor and plate segments 28b, c of the reactor. The resulting combined steam leaves the chamber 12 through the steam outlet 22. After leaving the plate segment 28a of the reactor, the reaction medium 60 flows downwards in the chamber 12 and is directed through the flow diverter 18b to the inlet 40b of the intermediate plate segment 28b of the reactor.

[0033] The flow of reaction medium 60 through the intermediate and lowest plate reactor segments 28b and 28c can proceed essentially the same as described above with respect to the flow through the highest plate segment 28a of the reactor. In brief, the reaction medium 60 passes through the plate segments 28a, b, c of the reactor as follows:

(a) the reaction medium 60 is directed from the chamber 12 to the plate segments 28a, b, c of the reactor through the flow deflectors 18a, b, c; (b) reaction medium 60 enters the plate segments 28a, b, c of the reactor through inlets 40a, b, c; (c) the reaction medium 60 generally flows from the chamber 12 into the shelves 48a, b, c; (d) the reaction medium 60 falls down through the ends of the shelves 48a, b, ci at the bottom of the tubular elements 44a, b, c; (e) the reaction medium 60 flows back towards the chamber 12 to the bottom of the tubular elements 44a, b, c; (e) the reaction medium 60 leaves the plate segments 28a, b, c of the reactor through the outlets 42a, b, c; and (f) the reaction medium 60 drops in the chamber 12 to the next processing level.

[0034] The reaction medium 60 leaving the lowest plate segment 28c of the reactor flows into the chamber 12 and is collected at its bottom. This final reaction medium 60 is discharged from the chamber 12 as a mainly liquid product through the liquid product outlet 24. [0035] Although not illustrated in FIG. 1, the impact plates can be used in the chamber 12 near one or more steam outlets 22, outlet 32 ​​of the non-plate reactor segment, and outlets 42a, b, c of plate reactor segments. Such impact plates can be placed in the vapor flow paths, so that the liquid entrained in the flowing steam strikes, accumulates and flows down from the impact plates. This helps ensure that only steam leaves the steam outlet 22 of the chamber 12.

[0036] With reference to FIG. 2, the second embodiment of the multilevel tubular reactor 100 is illustrated as generally comprising chamber 102, a first set of plate segments 104a, b, c, d of the reactor, and a second set of plate segments 106a, b, c, d of the reactor. In the configuration illustrated in FIG. 2, the first and second sets of segments 104a, b, c, di 106a, b, c, d of the reactor extend outwardly from generally opposite sides of the chamber 102. However, in an alternative embodiment, the reactor segment sets may extend from different sides of the chamber 102, which are not necessarily the opposite. For example, two sets of reactor segments may extend outward from the chamber at an angle of 45 °, 60 °, 75 °, 90 °, 105 °, 130 °, 145 °, or 160 ° relative to each other. In another example, the reactor 100 may use three sets of reactor segments circumferentially spaced around the chamber 102 at 120 ° angles to each other.

[0037] Again, according to FIG. 2, the chamber 102 includes a feed inlet 108 for receiving a feed charge, which may be in mainly liquid form, a product outlet 110 for draining mainly liquid product, and a pair of steam outlets 112a, b steam for draining steam. Chamber 102 generally includes a flow divider 114, a first set of flow deflectors 116a, b, c and a second set of flow deflectors 118a, b, c. The first and second set of segments 104a, b, c, di 106a, b, c, d reactor may have substantially the same configuration as the plate reactor segments described above with reference to

FIG. 1. Thus, the specific configuration and operation details of the plate segments 104a, b, c, di 106a, b, c, d of the reactor will not be described again.

[0038] In operation, the reactor 100 receives a feed, which can be mainly liquid, via feed inlet 108. Flow divider 114 divides the feed into two substantially equal parts. The flow divider 114 then directs one portion to the inner shelf of the uppermost first reactor segment 104a and the other part to the inner shelf of the uppermost second reactor segment 106a. When split portions of the feedstock enter the reactor tray segments, flow through the reactor tray segments may occur in substantially the same manner as described above with reference to FIG. 1, with the reaction medium moving along a flow path that includes an outwardly directed portion (i.e., outflow from the chamber into the inner shelf), downwardly directed portion (i.e., flow from the shelf to the bottom of the tubular member), and an inwardly directed portion (i.e., flow back towards the chamber at the bottom of the tubular element). After flowing through each reactor segment, the reaction medium is then directed through the chamber due to flow deflectors to the next lower reactor segment. Again according to FIG. 2, when the reaction medium leaves the lowest segments 104d and 106d of the reactor, both parts of the reaction medium combine to form mainly liquid product, which is withdrawn from the chamber 102 through the liquid product outlet 110.

[0039] With reference to FIG. 3, a third embodiment of the multilevel tubular reactor 200 is illustrated as comprising a horizontally elongated container jacket 202 and a shelf 204 disposed in the container jacket 202. The shelf 204 divides the inner volume of the container jacket 202 into the upper chamber 206 and the lower chamber 208. The container jacket 202 includes a horizontally elongated tubular element 210 and a pair of end caps 212,214 connected to opposite ends of the tubular element 210. The container jacket 202 includes a feed inlet 216, a liquid product outlet 218 and a steam outlet 220. The reactor 200 may have substantially the same configuration as the plate reactor segments described above with reference to FIG. 1 and 2.

[0040] During operation, the reactor 200 receives a feed charge, which can be mainly in liquid form, through the feed inlet 216. The feed charge of the reactor 200 forms the reaction medium 222 in the upper chamber 206 of the reactor 200. The reaction medium 222 flows through the upper chamber 206 after upper surface of shelf 204. When the reaction medium 222 reaches the distal end of the shelf 204, it falls onto the distal end of the shelf 204 and enters the lower chamber 208. The reaction medium 222 flows through the lower chamber 206 along the bottom of the tubular element 210 and towards the outlet 218 of the liquid product. Reaction medium 222 then leaves reactor 200 as mainly liquid product through product outlet 218. As illustrated by the full arrows in FIG. 3, the reaction medium 222 flows in generally opposite directions in the upper and lower chambers 206,208. As illustrated by the dashed arrows in FIG. 3, the vapors generated from the reaction medium 222 in the upper and lower chambers 206,208 can be combined and removed from the reactor 200 through the steam outlet 220.

[0041] Multilevel tubular reactors configured in accordance with certain embodiments of the present invention require little or no mechanical mixing of the reaction medium processed therein. Although the reaction medium processed in the multilevel tubular reactor can be rather mixed due to foaming, flowing through the reactor segments and falling from one reactor segment to another, such mixing by foaming, flow mixing and gravity mixing is not mechanical mixing. In one embodiment of the present invention, less than about 50 percent, less than about 25 percent, less than about 10 percent, less than about 5 percent, or 0 percent of the total mixing of the reaction medium occurring in the multilevel tubular reactor is provided by mechanical mixing. Thus, reactors configured in accordance with certain embodiments of the present invention can operate without any mechanical mixing devices. This is completely the opposite of that in conventional continuous mixing tank reactors (CSTR), which require almost exclusively mechanical mixing.

[0042] As indicated above, multi-stage tubular reactors configured in accordance with embodiments of the reactors of the present invention can be used in a wide variety of chemical processes. In one embodiment, a multi-stage tubular reactor configured in accordance with the present invention is used in a melt-phase polyester production plant capable of producing any of various polyesters from a variety of different substrates. Examples of melt phase polyesters that can be made according to embodiments of the present invention include, but are not limited to, polyethylene terephthalate (PET), which includes PET homopolymers and copolymers; fully aromatic or liquid crystalline polyesters; biodegradable polyesters such as polyesters containing butanediol, terephthalic acid and adipic acid residues; poly (cyclohexaneuterephthalate dimethylene) homopolymer and copolymers; and homopolymers and copolymers of 1,4-cyclohexane-dimethanol (CHDM) and cyclohexanedicarboxylic acid or dimethylcyclohexanedicarboxylate. When a PET copolymer is produced, such copolymer may comprise at least 90, at least 91, at least 92, at least 93, at least 94, at least 95, at least 96, at least 97, at least 98 mole percent repeating terephthalate units ethylene and up to 10, up to 9, up to 8, up to 7, up to 6, up to 5, up to 4, up to 3, or up to 2 mole percent of repeating units of added comonomer. Generally, the repeating comonomer units may be derived from one or more comonomers selected from the group consisting of isophthalic acid, 2,6-naphthalene dicarboxylic acid, CHDM and diethylene glycol.

[0043] In general, the method of producing polyester according to certain embodiments of the present invention may comprise two main steps - an esterification stage and a polycondensation stage. In the esterification step, polyester substrates, which may include at least one alcohol and at least one acid, are esterified to thereby produce polyester monomers and / or oligomers. In the polycondensation step, the polyester monomers and / or oligomers of the esterification step are reacted to the final polyester product. As used herein with respect to PET, monomers have less than 3 chain lengths, oligomers have from about 7 to about 50 chain lengths (components with a chain length of 4 to 6 units can be considered a monomer or oligomer), and polymers have more than about 50 chain lengths. The dimer, for example, EG-TA-EG-TA-EG, has a chain length of 2, and trimer 3, and so on.

[0044] The acid substrate used in the esterification step may be a dicarboxylic acid such that the final polyester product comprises at least one dicarboxylic acid residue having from about 4 to about 15 or from 8 to 12 carbon atoms. Examples of dicarboxylic acids suitable for use in the present invention may include, but are not limited to, terephthalic acid, phthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, cyclohexanedicarboxylic acid, cyclohexanediacetic acid, diphenyl-4,4'-dicarboxylic acid , diphenyl-3,4'-dicarboxylic acid, 2,2-dimethyl-1,3-propanediol, dicarboxylic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid and mixtures thereof. In one embodiment, the acid substrate may be a suitable ester such as dimethyl terephthalate instead of terephthalic acid.

[0045] The alcohol substrate used in the esterification step may be a diol such that the final polyester product may include at least one diol residue, such as, for example, those derived from cycloaliphatic diols having from about 3 to about 25 carbon atoms or 6 to 20 atoms coal. Suitable diols may include, but are not limited to, ethylene glycol (EG), diethylene glycol, triethylene glycol, 1,4-cyclohexane-dimethanol, propane-1,3-diol, butane-1,4-diol, pentane-1 , 5-diol, hexane-1,6-diol, neopentyl glycol, 3-methylpentanediol- (2,4), 2-methylpentanediol- (1,4), 2,2,4-trimethylpentane-diol- (1,3), 2- ethylhexanediol- (1,3), 2,2-diethyl propane-diol- (1,3), hexanediol- (1,3), 1,4-di- (hydroxyethoxy) -benzene, 2,2-bis- (4-hydroxycyclohexyl) - propane, 2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane, 2,2,4,4-tetramethyl-cyclobutanediol, 2,2-bis- (3-hydroxyethoxyphenyl) propane, 2,2-bis- (4-hydroxy -propoxyphenyl) -propane, isosorbide, hydroquinone, BDS- (2,2- (sulfonylbis) 4,1-phenyleneoxy)) bis (ethanol), and mixtures thereof.

[0046] In addition, the substrates may include one or more comonomers. Suitable comonomers may include, for example, comonomers including terephthalic acid, dimethyl terephthalate, isophthalic acid, dimethyl isophthalate, dimethyl 2,6-naphthalene dicarboxylate, 2,6-naphthalene dicarboxylic acid, ethylene glycol, diethylene glycol, 1,4-cyclohexane-dimethanol (CHDM) 1,4-butanediol, polytetramethylene glycol, trans-DMCD, trimellitic anhydride, dimethyl cyclohexane-1,4-dicarboxylate, dimethyl decaline-2,6-dicarboxylate, decalinedimethanol, Decahydronaphthalate 2,6-dicarboxylate, 2,6-dihydroxymethyl-decahydronaphthalene, hydroquinone, hydroxybenzoic acid and mixtures thereof.

[0047] The esterification step and the polycondensation step of the melt-phase polyester production process may include multiple steps. For example, the esterification step may include an initial esterification step for producing a partially esterified product, which is then further esterified in a secondary esterification step. Also, the polycondensation step may include a pre-polymerization step to produce a partially condensed product, which is then subjected to a finishing step to thereby produce the final polymer product.

[0048] Reactors configured in accordance with certain embodiments of the present invention can be used in the melt-phase polyester production system as a secondary esterification reactor for conducting the secondary esterification stage, as a prepolymer reactor for conducting the pre-polymerization stage, and / or as a finishing reactor for conducting the stage finishing. A detailed description of the process conditions for the present invention used as esterification reactor, prepolymer reactor and / or finishing reactor is given below with reference to FIG. 1. It is understood that reactors configured in accordance with embodiments of the present invention can generally be used as esterification reactors, prepolymer reactors, and / or finishing reactors and that these process conditions are not limited to the embodiments described in FIG. 1, [0049] Again, according to FIG. 1, when reactor 10 is used as a secondary esterification reactor in a melt phase polyester production method (e.g., a PET production method), more than one chemical reaction may be carried out in the reactor 10. For example, although the esterification may be the primary chemical reaction carried out in the reactor 10, some polycondensation may also take place in the reactor 10. When reactor 10 is used as a secondary esterification reactor, the feed charge introduced into the feed inlet 30 of reactor segment 26 may have a degree of conversion in the range of about 70 to about 95 percent, about 75 to about 90 percent, or 80 to 88 percent, while mainly the liquid product discharged from the outlet 24 of the liquid product of the chamber 12 may have a degree of conversion of at least about 80 percent, at least about 90 percent, at least about 95 percent, or at least 98 percent. When reactor 10 is used as a secondary esterification reactor, the chemical reaction (s) carried out in reactor 10 may increase the conversion of reaction medium 60 by at least about 2 percentage points, at least about 5 percentage points, or at least 10 percentage points between the feed inlet 30 and outlet 24 liquid product. In addition, the average length of the feed chain entering the feed inlet 30 may be less than about 5, less than about 2 or less than 1, while mainly liquid product discharged from the outlet of the liquid product may have an average chain length in the range of about 1 to about 20, about 2 to about 12, or 5 to 12. Generally, when reactor 10 is used as secondary esterification reactor, the average chain length of reaction medium 60 may increase in the range of from about 1 to about 20, about 2 to about 15, or 5 to 12 between feed inlet 30 and liquid product outlet 24.

[0050] When the reactor 10 is used as a secondary esterification reactor, the feed charge of the reactor 10 may enter the feed inlet at a temperature in the range of about 180 to about 350 ° C, about 215 to about 305 ° C, or 260 to 290 ° C . The mainly liquid product leaving the liquid product outlet 24 may have a temperature in the range of about 50 ° C, 25 ° C, or 10 ° C from the temperature of the feed entering the feed inlet 30. In one embodiment, the temperature of the liquid product leaving the liquid product outlet 24 may range from about 180 to about 350 ° C, about 215 to about 305 ° C, or 260 to 290 ° C. In one embodiment, the average temperature of reaction medium 60 in reactor 10 is in the range of from about 180 to about 350 ° C, about 215 to about 305 ° C, or 260 to 290 ° C. The average temperature of the reaction medium 60 is the average of at least three temperature measurements taken at equal intervals along the original flow path of the reaction medium through the reactor 10, where the temperature measurements are taken near the center of gravity of the cross section of the portion being mainly liquid 66 of the reaction medium 60 (in contrast to the vicinity of the wall reactor or near the upper surface of the part being mainly liquid). When the reactor 10 is used as a secondary esterification reactor, the vapor space pressure in the reactor 10 (measured at the steam outlet 22) can be kept less than about 70 psig, in the range from about -4 to about 10 psig, or in the range from 2 to 5 psig.

[0051] When the reactor 10 is used as secondary esterification reactor, it may be desirable to heat the feed prior to entering reactor 10 and / or it may be desirable to heat the reaction medium 60 as it flows through the reactor 10. Heating the feed prior to entering reactor 10 may be run in a conventional heat exchanger such as, for example, a shell and tube heat exchanger. Heating of the reaction medium 60 in the reactor 10 can be carried out by external heating devices in contact with the reactor 10 but not extending into the reactor 10. Such internal heat exchange devices include, for example, jackets and / or line heating. Generally, the cumulative amount of heat added to the feed charge immediately after reactor 10 plus heat added to reaction medium 60 in reactor 10 may range from about 232.6 to about 11630 kJ / kg (about 100 to about 5000 BTU per pound) medium Reaction range from about 930.4 to about 4652 kJ / kg (about 400 to about 2000 BTU / lb) or in the range of 1395.6 to 3489 kJ / kg (from 600 to 1500 BTU / lb).

[0052] Again, according to FIG. 1, when the reactor 10 is used as a prepolymer reactor in a melt phase polyester production process (e.g., a PET production method), more than one chemical reaction can be carried out in the reactor 10. For example, although polycondensation may be the predominant chemical reaction carried out in reactor 10, some of the esterification may also take place in reactor 10. When reactor 10 is used as a prepolymer reactor, the average feed chain length fed to feed inlet 30 may range from about 1 to about 20, about 2 to about 15, or 5 to 12, while the average chain length of mainly liquid product the liquid product discharged from the outlet 24 may range from about 5 to about 50, about 8 to about 40, or 10 to 30. When the reactor 10 is used as a prepolymerization reactor, the chemical reaction carried out in the reactor 10 may cause an increase in the average chain length of the reaction medium 60 by at least about 2, in the range of from about 5 to about 30, or in the range from 8 to 20 between feed inlet 30 and an outlet 24 liquid product.

[0053] When the reactor 10 is used as a prepolymer reactor, the feed charge may enter the feed inlet at a temperature in the range of about 220 to about 350 ° C, about 265 to about 305 ° C, or 270 to 290 ° C. The mainly liquid product leaving the liquid product outlet 24 may have a temperature in the range of about 50 ° C, 25 ° C, or 10 ° C from the temperature of the feed entering the feed inlet 30. In one embodiment, the temperature of the liquid product leaving the liquid product outlet 24 is in the range of from about 220 to about 350 ° C, about 265 to about 305 ° C, or 270 to 290 ° C. In one embodiment, the average temperature of reaction medium 60 in reactor 10 is in the range of from about 220 to about 350 ° C, about 265 to about 305 ° C, or 270 to 290 ° C. When the reactor 10 is used as a prepolymer reactor, the vapor space pressure in the reactor 10 (measured at the steam outlet 22) can be maintained in the range of from about 0 to about 40 kPa (about 0 to about 300 torr), in the range of about 0 , 1 to about 6.6 kPa (1 to about 50 tracks), or in the range from 2.6 to 4 kPa (20 to 30 tracks).

[0054] When the reactor 10 is used as a prepolymer reactor, it may be desirable to heat the feed prior to entering the reactor 10 and / or it may be desirable to heat the reaction medium 60 as it flows through the reactor 10. Generally, the cumulative amount of heat added to the feed just before reactor 10 plus heat added to reaction medium 60 in reactor 10 may range from about 232.6 to about 11630 kJ / kg (100 to about 5,000 BTU / lb), in range from approx

930.4 to about 4652 kJ / kg (400 to about 2.000 BTU / lb), or in the range from 1395.6 to 3489 kJ / kg (600 to 1.500 BTU / lb).

[0055] Again according to FIG. 1, when the reactor 10 is used as a finishing reactor in a melt-phase polyester production method (e.g., a PET production method), the average feed chain length fed to feed inlet 30 may range from about 5 to about 50, about 8 to about 40, or 10 to 30, while the average chain length of the mainly liquid product discharged from the liquid product outlet 24 may range from about 30 to about 210, about 40 to about 80, or 50 to 70. Generally, polycondensation carried out in the reactor 10 may cause an increase in the average chain length of reaction medium 60 by at least about 10, at least about 25, or at least 50 between feed inlet 30 and liquid product outlet 24.

[0056] When the reactor 10 is used as a finishing reactor, the feed charge may enter the feed inlet at a temperature in the range of about 220 to about 350 ° C, about 265 to about 305 ° C, or 270 to 290 ° C. The mainly liquid product leaving the liquid product outlet 24 may have a temperature in the range of about 50 ° C, 25 ° C, or 10 ° C from the temperature of the feed entering the feed inlet 30. In one embodiment, the temperature of the liquid product leaving the liquid product outlet 24 is in the range of from about 220 to about 350 ° C, about 265 to about 305 ° C, or 270 to 290 ° C. In one embodiment, the average temperature of reaction medium 60 in reactor 10 is in the range of from about 220 to about 350 ° C, about 265 to about 305 ° C, or 270 to 290 ° C. When the reactor 10 is used as a finishing reactor, the pressure in the vapor space in the reactor 10 (measured at the steam outlet 22) can be maintained in the range from about 0 to about 40 kPa (about 0 to about 30 torr), in the range from about 0, 13 to about 2.6 kPa (about 1 to about 20 tracks), or in the range from 0.26 to 1.3 kPa (2 to 10 tracks).

[0057] Reactors configured in accordance with embodiments of the present invention can provide numerous advantages when used as reactors in the esterification and / or polycondensation steps of a polyester production method. Such reactors can be particularly advantageous when used as secondary esterification, prepolymer and / or finishing reactors in a PET production process. In addition, such reactors are well suited for use in industrial scale PET production installations capable of producing PET in an amount of at least about 4536 kg (10,000 pounds) per hour, at least about 45360 kg (100,000 pounds) per hour, at least about 113398 kg (250,000 pounds) per hour, or at least 226796 kg (500,000 pounds) per hour.

[0058] In one embodiment of the present invention, a method is provided comprising subjecting a reaction medium to a chemical reaction in a reactor comprising a first horizontally elongated reactor segment through which the reaction medium flows as the reaction medium passes through the reactor. The first reactor segment includes a first horizontally elongated tubular element and a first shelf disposed substantially in the first tubular element and extending along at least half, at least three quarters, or at least nine tenths of the length of the first tubular element. At least a portion of the reaction medium flows in one direction to the first tray and in a generally opposite direction to the bottom of the first tubular element.

[0059] In one example, the reactor further includes a chamber to which the proximal end of the first reactor segment is connected, wherein the first reactor segment receives the reaction medium on the first shelf from the chamber, wherein the first reactor segment drains the reaction medium to the chamber from the bottom of the first element tube.

In addition, the first reactor segment can discharge the by-product in the form of chemical reaction vapor into the chamber, wherein the discharged by-product flows generally upwards in the chamber, while the discharged reaction medium generally flows downwards in the chamber.

[0060] In another example, the reaction medium flows to the first shelf from the proximal end to the distal end of the first shelf, wherein the reaction medium flows through the distal end of the first shelf and to the bottom of the first tubular element. In addition, the distal end of the first shelf may include an upward overhang over which, through which, around which and / or under which at least part of the reaction medium flows before passing to the bottom of the first tubular element. In another example, the first reactor segment includes a closing cap connected to the distal end of the first tubular element, the distal end of the first shelf being horizontally spaced from the closing cap, thereby forming a flow channel through which the reaction medium flows when the reaction medium passes from the first shelf to the bottom of the first tubular element.

[0061] In one example, the first tubular element and the first shelf are substantially horizontally oriented. In another example, the first tubular element is a pipe. The first reactor segment may have a length to diameter ratio (L: D) in the range of from about 2: 1 to about 50: 1, about 5: 1 to about 20: 1, or 8: 1 to 15: 1. In one example, in addition, L is in the range of from about 3.05 to about 60.96 m (about 10 to about 200 feet), about 6.1 to about 30.48 m (about 20 to 100 feet), or (9.14 to 15.24 m) (30 to 50 feet), and D is in the range of about 3.05 to about 6.1 m (about 1 to about 20 feet), 1395.6 to 3489 kJ / kg (about 2 to about 10 feet), or 0.91 to 1.52 m (3 to 5 feet).

[0062] In yet another example, the reactor further includes a second horizontally elongated reactor segment through which at least a portion of the reaction medium flows as the reaction medium travels through the reactor, the second reactor segment being vertically positioned below the first reactor segment, wherein the reactor comprises a chamber with which the first and second reactor segments are connected at different heights, wherein the reaction medium flows down through the chamber as the reaction medium moves from the first reactor segment to the second reactor segment. The second reactor segment may include a second elongated tubular element and a second shelf disposed substantially in the second tubular element, the second shelf extending along at least half, at least three-quarters, or at least nine-tenths of the length of the second tubular element, at least a portion of the reaction medium flows in one direction on the other inner shelf and in a generally opposite direction on the bottom of the other tubular element. In one example, the reactor comprises a further first and second flow diverter connected to the first and second tray, respectively, and extending into the chamber, the second flow diverter directing the reaction medium leaving the first tubular element through the chamber and onto the second tray. In addition, the steam pause may be between the first and second flow deflectors, the steam pause allowing the byproduct to flow as a vapor from a chemical reaction from the second reactor segment and up through the chamber while the reaction medium exits the first reactor segment is directed down to the second reactor segment.

[0063] In one example, a byproduct in the form of a vapor reaction from a chemical carried out in the first and second segment of the reactor is combined in the chamber and leaves the reactor through a steam outlet located near the top of the chamber. In addition, mainly the liquid chemical reaction product can leave the reactor through a liquid outlet located near the bottom of the chamber.

[0064] In one example, the chamber has a height to width ratio (H: W) ranging from about 2: 1 to about 20: 1, about 4: 1 to about 15: 1, or 5: 1 to 10: 1, wherein the first and second reactor segments have an L: D ratio in the range of from about 2: 1 to about 50: 1, about 5: 1 to about 20: 1, or 8: 1 to 15: 1.

[0065] In one example, the chamber extends substantially vertically (i.e., the central axis of extension of the chamber is substantially vertical). Alternatively, the chamber may deviate by about 30, about 15, or 5 degrees from the vertical. In one example, the reactor segments extend substantially horizontally (i.e., the central axis of extension of the reactor segments is substantially horizontal). Alternatively, the reactor segments may deviate by about 30, about 15, or 5 degrees from level. In another example, the reactor does not contain a mechanical mixing device.

[0066] In one example, in addition to the second reactor segment, the reactor further includes a third horizontally elongated reactor segment through which at least a portion of the reaction medium flows as the reaction medium moves through the reactor, the third reactor segment vertically spaced below the second a reactor segment, the third reactor segment comprising a third elongated tubular element and a third shelf disposed substantially in the third tubular element, wherein the third shelf extends along at least half, at least three-quarters, or at least nine-tenths of the length of the third tubular element, wherein at least a portion of the reaction medium flows in one direction on the third internal shelf and in a generally opposite direction on the bottom of the third tubular element , wherein the third reactor segment is connected to the chamber, the reaction medium flowing down through the chamber, when the reaction medium moves from the second reactor segment to the third reactor segment.

[0067] In one example, the reaction medium comprises a liquid in which a chemical reaction is carried out. In another example, the reaction medium includes a foam portion and a predominantly liquid portion, each containing a liquid. In yet another example, the reactor comprises a plurality of horizontally elongated reactor segments, wherein a portion of the reaction medium placed in the highest of many reactor segments contains at least 50 volume percent steam and a portion of the reaction medium located in the lowest of many reactor segments contains less than 20 volume percent steam .

[0068] In one example, the chemical reaction comprises polycondensation, wherein the average chain length of the reaction medium increases by at least about 10, at least about 25, or at least 50 in the reactor. In one example, the reaction medium may comprise a polyester polymer or copolymer that is at least partially formed by polycondensation. The polymer or polyester copolymer may include polyethylene terephthalate (PET). In addition, the method may include introducing the polycondensation feed into the reactor feed inlet, the polycondensation feed forming the reaction medium in the reactor. The polycondensation feed may have an average chain length in the range of from about 5 to about 50, about 8 to about 40, or 10 to 30.

[0069] In another example of the present invention, a method is provided comprising subjecting the reaction medium to an esterification and / or polycondensation reaction in a reactor comprising a horizontally elongated reactor segment through which the reaction medium flows as the reaction medium passes through the reactor. The reactor segment comprises a horizontally elongated tubular element and a shelf disposed substantially in the tubular element and extending along at least half, at least three quarters, or at least nine tenths of the length of the tubular element. At least a portion of the reaction medium flows in one direction to the tray and in a generally opposite direction at the bottom of the tubular element. Detailed description of FIG. 1 the reactor 10 used as the second stage esterification, prepolymerization and / or finishing reactor given above applies to this example of the present invention. Specifically the feed charge characteristics (e.g., conversion and / or chain length), temperature, pressure, conversion increase, increase in average chain length, product characteristics and any heating cartridge are fully applied to this example of the present invention.

[0070] In one example, the product is removed from the reactor product outlet, wherein the reaction medium produces the product in the reactor. In addition, when the chemical reaction involves polycondensation, the product may be a polycondensation product. It.V. the polycondensation product or product may range from about 0.3 to about 1.2, about 0.35 to about 0.6, or 0.4 to 0.5 dl / g. In one example, It.V. the polycondensation product or product is in the range of from about 0.1 to about 0.5, about 0.1 to about 0.4, or 0.15 to 0.35 dl / g. In one example, the feed is fed into the reactor feed inlet to form the reaction medium and It.V. the feed charge is in the range of from about 0.1 to about 0.5, about 0.1 to about 0.4, or

0.15 to 0.35 dl / g.

[0071] Intrinsic viscosity (It.V.) values ​​are given in units dl / g calculated from the inherent viscosity measured at 25 ° C in 60% phenol and 40% 1,1,2,2-tetrachloroethane, by weight. Polymer samples can be dissolved in the solvent at a concentration of 0.25 g / 50 ml. The viscosity of polymer solutions can be determined, for example , using a Rheotek glass capillary viscometer. A description of how this viscometer works can be found in ASTM D 4603. The logarithmic viscosity number is calculated from the measured solution viscosity. The following equations describe such measurements of solution viscosity and further calculations to Ih.V. and from Ih.V. to It.V:

T] inh - [In (vol_s/ to)] / C where n_inh = logarithmic viscosity number at 25 ° C with a polymer concentration of 0.5 g / 100 ml 60% phenol and 40% 1,1,2,2-tetrachloroethane, weight ln = natural logarithm ts = sample flow time through the capillary tube = solvent blank flow time through the capillary tube C = polymer concentration in grams per 100 ml solvent (0.50%) [0072] The intrinsic viscosity is the limit at infinite dilution of the intrinsic viscosity of the polymer. It is defined by the following equation:

nint = lim (nsp / C) = lim (Ιηη_C.) / Ο C-> 0 C-> 0 where n_int = intrinsic viscosity η = relative viscosity = t_s/ t_about n_sp = intrinsic viscosity = n_r - [0073] Intrinsic viscosity (It.V. or n_int) can be estimated using the Billmeyer equation as follows:

<img file="PL2178634T3_D0001.tif" />

The reference for estimating the intrinsic viscosity (Billmeyer relationship) is J.

Polymer Sci., 4, pp. 83-86 (1949).

[0074] Viscosity of polymer solutions can also be determined using a Viscotek Modified Differential Viscometer viscometer (for a description of how manometric viscometers work, see ASTM D 5225) or other methods known to those skilled in the art.

[0075] In another embodiment of the present invention, there is provided a method of producing polyethylene terephthalate (PET) comprising: (a) introducing a polycondensation feed into a polycondensation reactor, wherein the polycondensation feed feed forms a reaction medium in the reactor, wherein the feed polycondensation feed includes PET having an average chain length in the range of from about 5 to about 50, about 8 to about 40, or 10 to 30; (b) subjecting the polycondensation reaction medium to the reactor, the reactor comprising a vertically elongated chamber and at least two horizontally elongated vertically spaced reactor segments connected and projecting out of the chamber, the chamber providing fluid flow between the reactor segments, the reaction medium passes down through the chamber when the reaction medium moves from one reactor segment to another, each reactor segment includes an elongated tube and a shelf disposed substantially in the tube, the tube and shelf being substantially horizontally oriented, the tube having a length to diameter ratio (L: D) ranging from about 2: 1 to about 50: 1 , or about 5: 1 to about 20: 1 or 8: 1 to 15: 1, wherein the shelf has a length of at least about 0.5L, at least about 0.75L, or at least 0.9L, wherein at least a portion of the reaction medium flows in one direction onto the shelf and in a generally opposite direction at the bottom of the pipe; and (c) recovering mainly the liquid polycondensation product from the reactor, the polycondensation product comprising PET having an average chain length that is at least about 10, at least about 25, or at least 50 greater than the average PET chain length in the polycondensation feed.

[0076] In one example of the method for producing PET, the reaction medium comprises a foam portion and a predominantly liquid portion.

[0077] In one example, the reactor segments extend from generally the same side of the chamber. In another example, the reactor segments extend from generally opposite sides of the chamber.

[0078] In one example, the shelf includes an upwardly directed flow surface through which the reaction medium flows, wherein the upwardly directed flow surface is at least about 0.1D away, at least about 0.2D away, or at least 0, 4D from the top and / or bottom of the tubular element. In another example, the upward surface is about 5 to about 50 inches away, about 10 to about 40 inches, or 15 to 30 inches from the top and / or bottom of the tubular element. In one example, the maximum depth of reaction medium on each shelf and / or bottom of each tubular element is less than about 0.8D, less than about 0.4D, or less than 0.25D. The maximum depth of reaction medium on each shelf and / or bottom of each tubular element can be about 2.54 to about 101.6 cm (about 1 to about 40 inches), about

2.54 to about 81.28 cm (about 1 to about 32 inches), or 2.54 to 60.96 cm (1 to 24 inches).

[0079] In another example, the polycondensation results in the formation of a steam by-product, wherein the steam by-product is discharged from the polycondensation reactor through a steam outlet located near the top of the chamber, wherein the polycondensation product is recovered from a liquid outlet located near the bottom chamber.

[0080] In one example, It.V. polycondensation feed charge ranges from about 0.1 to about 0.5, about 0.1 to about 0.4, or about 0.15 to about 0.35 dl / g. In one example, It.V. the polycondensation product ranges from about 0.3 to about 1.2, about 0.35 to about 0.6, or 0.4 to 0.5 dl / g.

[0081] In a further embodiment of the present invention, a reactor is provided comprising a first horizontally elongated reactor segment. The first reactor segment includes a first elongated tubular element and a first shelf disposed substantially in the first tubular element. The first shelf extends along at least half, at least three-quarters, or at least nine-tenths of the length of the first tubular element and divides the inside of the first tubular element into the first upper and lower chamber. The first reactor segment includes an internal flow channel near one end of the first reactor segment to allow fluids to pass between the first upper and lower chamber.

[0082] In one example, the first reactor segment includes a first closing cap connected to the first tubular element at one end. In another example, the first shelf does not extend the entire length into the closing cap, such that the first internal flow channel is the gap between the first shelf and the first closing cap. In addition, the first reactor segment may include an upwardly projecting overflow connected to the first tray close to the first internal flow channel.

[0083] In another example, the first tubular element has a length to diameter ratio (L: D) in the range of from about 2: 1 to about 50: 1, about 5: 1 to about 20: 1, or 8: 1 to 15: 1. Additionally, the first shelf may have a length of at least about 0.5L, about 0.75L, or 0.9L, the first shelf having an upwardly directed flow surface distant from the top and / or bottom of the tubular element by a vertical distance in the range of about 0 , 9 D to about 0.9D, about 0.2D to about 0.8D, or 0.4D to 0.6D. In another example, the upward surface is about 5 to about 50 inches, about 10 to about 40 inches, or 15 to 30 inches from the top and / or bottom of the tubular element. In one example, the maximum depth of reaction medium on each shelf and / or bottom of each tubular element is less than about 0.8D, less than about 0.4D, or less than 0.25D. The maximum depth of reaction medium on each shelf and / or bottom of each tubular element can be about 2.54 to 101.6 cm (about 1 to about 40 inches), about 2.54 to about 81.28 cm (about 1 to about 32 inches), or 2.54 to 60.96 cm (1 to 24 inches). In one example, the first tubular element includes a pipe.

[0084] In addition, the pipe and first shelf may be substantially horizontally oriented.

[0085] In one example, the reactor further includes a vertically elongated chamber, one end of the first reactor segment being spaced from the chamber, the opposite end of the first reactor segment being connected to the chamber. In addition, the first upper and lower chambers can be connected to fluid flow with the chamber at the opposite end of the first reactor segment.

[0086] In one example, the length to diameter ratio (L: D) of the first tubular element is in the range of from about 2: 1 to about 50: 1, about 5: 1 to about 20: 1, or 8: 1 to 15: 1, wherein L is in the range of about 3.05 to about 60.96 m (about 10 to about 200 feet), about 6.1 to about 30.48 m (about 20 to about 100 feet), or , 14 to about 15.24 m (30 to 50 feet) and D is in the range of about 0.31 to about 6.1 m (about 1 to about 20 feet), about 0.62 to about 3.05 m (about 2 to about 10 feet), 0.91 to

1.52 m (3 to 5 feet) with the chamber having a ratio of height to width (H: W) in the range from about 2: 1 to about 20: 1, about 4: 1 to about 15: 1, or 5: 1 up to 10: 1, wherein H is in the range of from about 2.44 to about 30.48 m (about 8 to about 100 feet) about 3.05 to about 22.86 m (about 10 to 75 feet) or 6 , 1 to 15.2 m (20 to 50 feet) and W ranges from about 0.31 to about 6.1 m (about 1 to about 20 feet) about 0.62 to about 3.05 m (about 2 to about 10 feet), or 0.91 to 1.52 m (3 to 5 feet) [0087] In one example, the reactor further includes a second horizontally elongated reactor segment connected and projecting out of the chamber, the second reactor segment being spaced apart vertically below the first reactor segment. The first and second reactor segments may project outwardly from generally the same side of the chamber or from generally opposite sides of the chamber.

[0088] In one example, the second reactor segment has a proximal end connected to the chamber and a distal end distant from the chamber, the second reactor segment comprising a second elongated tubular element and a second shelf substantially located in the second tubular element, the second shelf extending along at least half, at least three quarters, or at least nine-tenths of the length of the second tubular element and divides the inside of the second tubular element into a second upper and lower chamber, the second upper and lower chamber being in communication with fluid flow with the chamber at the proximal end, the second reactor segment having a second internal a flow channel near the distal end to allow fluid to pass between the second upper and lower chambers. In addition, the reactor may include a first and a second flow diverter connected to the first and second trays, respectively, and extending into the chamber. In one example, the steam gap is in the second flow diverter or between the first and second flow diverter at an elevation above the elevation of the second reactor segment.

[0089] In one example, the reactor further includes a third horizontally elongated reactor segment connected and projecting out of the chamber, the third reactor segment vertically spaced below the second reactor segment. The first, second and third reactor segments may have substantially identical configurations.

Numerical ranges [0090] The present description uses numerical ranges to quantify certain parameters related to the invention. It should be understood that when numerical ranges are given, such ranges should be interpreted as providing literal support for the restrictions of the claims listing only the lower value of the range, as well as the restrictions of the claims listing only the upper value of the range. For example, the disclosed numerical range of 10 to 100 provides literal support for the listing item "more than 10" (without upper limits) and the listing item "less than 100" (without lower limits).

Definitions [0091] As used herein, the terms "certain", "this" and "said" mean one or more.

[0092] As used herein, the term "mixing" refers to work dispersed in a reaction medium causing fluid flow and / or mixing.

[0093] As used herein, the term "and / or" as used in a list of two or more items means that any of the items listed may be used as such, or any combination of two or more of the items listed may be used. For example, if the composition is described as comprising components A, B, and / or C, the composition may contain A alone; same B; same C; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination.

[0094] As used herein, the term "average chain length" means the average number of repeating units in the polymer. For polyester, the average chain length means the number of repeating units of acid and alcohol. The average chain length is synonymous with the number average degree of polymerization (DP). The average chain length can be determined by various means known to those skilled in the art. For example, 1H-NMR can be used to directly determine the chain length based on end group analysis, and light scattering can be used to measure the weight average molecular weight with correlations used to determine the chain length. Chain length is often calculated based on correlations with gel permeation chromatography (GPC) measurements and / or viscosity measurements.

[0095] As used herein, the terms "include cy", "includes" and "include" are open transition terms used to transition from a named entity before defining to one or more of the elements listed after determining where the element or more elements listed after the transitional period are not necessarily the only elements that make up the entity.

[0096] As used herein, the terms "containing cy", "comprises" and "contain" have the same open meanings as "including", "includes" and "include" as set out below.

[0097] As used herein, the term "conversion" is used to describe the liquid phase properties of a stream that has been esterified, wherein the degree of conversion of the esterified stream indicates the percentage of the original acid end groups that have been transformed (i.e., esterified) to ester groups. The conversion can be quantified as the number of transformed end groups (i.e., alcohol end groups) divided by the total number of end groups (i.e., alcohol plus acid end groups), expressed as a percentage.

[0098] As used herein, the term "directly connected" refers to a method of connecting two containers connected to each other with a fluid flow without the use of an intermediate connector having a substantially narrower diameter than both containers.

[0099] As used herein, the term "esterification" refers to esterification and transesterification reactions.

[0100] As used herein, the terms "have", "has" and "have" have the same open meaning as "including," "includes," and "include," set out above.

[0101] As used herein, the term "horizontally elongated" means that the maximum horizontal dimension is greater than the maximum vertical dimension.

[0102] As used herein, the terms "including," "including," and "including" have the same open meanings as "including," "includes," and "include," described above.

[0103] As used herein, the term "mechanical mixing" refers to the mixing of a reaction medium caused by the physical movement of a rigid or flexible element (s) against or within the reaction medium.

[0104] As used herein, the term "open flow field" refers to an open field available for fluid flow, where the open field is measured along a plane perpendicular to the direction of flow through the opening.

[0105] As used herein, the term "pipe" refers to a substantially straight elongated tubular element having a generally cylindrical sidewall. [0106] As used herein, the terms "polyethylene terephthalate" and "PET" include PET homopolymers and PET copolymers.

[0107] As used herein, the terms "polyethylene terephthalate copolymer" and "PET copolymer" mean PET that has been modified by up to 10 mole percent of one or more additional comonomers. For example, the terms "polyethylene terephthalate copolymer" and "PET copolymer" include PET modified to 10 mole percent isophthalic acid to 100 mole percent carboxylic acid. In another example, the terms "polyethylene terephthalate copolymer" and "PET copolymer" include PET modified to 10 mole percent 1,4-cyclohexanedimethanol (CHDM) per 100 mole percent diol.

[0108] As used herein, the term "polyester" refers not only to traditional polyesters, but also includes polyester derivatives such as, for example, polyether ester, polyester ester and polyether polyester ester.

[0109] As used herein, "mainly liquid" means more than 50 percent by volume of liquid.

[0110] As used herein, the term "reaction medium" refers to any medium that undergoes a chemical reaction.

[0111] As used herein, the term "residue" refers to a moiety that is the final product of a chemical compound in a particular reaction scheme or subsequent chemical preparation or product, regardless of whether the moiety is indeed derived from chemical compounds.

[0112] As used herein, the term "vapor by-product" includes steam generated by a desired chemical reaction (i.e. a steam co-product) and any steam generated by other reactions (i.e. side reactions) of the reaction medium.

[0113] As used herein, the term "vertically elongated" means that the maximum vertical dimension is greater than the maximum horizontal dimension.

Claims not limited to the disclosed embodiments [0114] The exemplary embodiments of the invention described above are used only as an illustration and should not be used in a limiting sense to interpret the scope of the claimed invention. Various modifications to the above-described exemplary embodiments can easily be made by those skilled in the art without departing from the scope of the invention as set out in the following claims.